I use the notion of percentage error to forefront what others have
mentioned, that in the measurement process, equality is not the issue.
Indeed, in science, equality is not the issue since the foundation, from
my perspective is measurement. This issue rather is, are two values
close enough that we are willing to say they are the same? The answer to
that question naturally leads to discussions of multiple
measurements.For example,.how can you compare two values from two
different
circumstances, when you don't know how to compare values for th same
circumstance...this leads to issues of precision.
I frankly haven't thought deeply about the real meaning of percent error,
I just know it is a good pedagogical tool for getting to issues of how
science differs from mathematics, where of course, equility is the issue.